After Reading the Paragraph Below, Answer the Question That Follows

After reading the paragraph below, answer the question that follows.
Mould can be a huge problem in houses. In hot, humid climates like Florida entire houses have had to be thoroughly renovated or even completely abandoned due to the presence of moulds. Thus, understanding and mitigating mould contamination is of significant importance.
-What aspect of mould biology can be particularly problematic to people?

A) their ability to digest wood and thus weaken structures
B) their unsightly appearance
C) the formation of airborne spores which, if inhaled or ingested, can cause an allergic response
D) their slippery texture underfoot